Temperature and initial polarization dependences of the electrooptic coefficient of BaTiO3 crystal film

In this work, the temperature dependence of polarization degree of ferroelectric phase barium titanate (BaTiO 3 ) film is first modelled based on a conservation of the energy-focusing cost of a microstructural domain cell, and then the dual dependences on both temperature and initial polarization degree of an off-axis tensor electrooptic coefficient ( r 51 ) is modelled. Further, the correlation between the initial polarization degree and the r 51 is investigated based on the correlative electrooptic and elasto-optic effects of a perovskite crystal. With the output of theoretical models for the attributes of r 51 , numerical simulations are carried out. It was found that both the polarization degradation of out-of-plane polarization ( P z ) and the electrooptic coefficient r 51 of c-axis oriented crystal films exhibit significant nonlinear dependences on the initial fraction of in-plane polarization ( P x ) and the working temperature. Consequently, the temperature dependences of the measured results of r 51 with respect to the selected working temperatures in the range of 20°C∼100°C are consistent with the above numerical results, showing that the out-of-plane polarization degree presents the biggest degradation in the temperature range from 50°C to 70°C. This work provides a valuable reference to the research and development of high-speed electro-optic devices and applications.